British Foreign Secretary Boris Johnson gives a speech during a Chatham House conference in central London on October 23, 2017. (Photo by AFP)

British Foreign Secretary Boris Johnson has said US military action against North Korea “must theoretically remain on the table” defending President Donald Trump’s attitude towards the country.

“It is the duty of any president of the US given the threat that his or her country could face from a nuclear-armed North Korea, it is the duty of the President at least to explore those military options and keep them on the table,” he said Monday, speaking at an event in central London held by the foreign policy think tank Chatham House.

“I’m afraid that the US president, whoever he or she might be, will have an absolute duty to prepare any option to keep safe not only the American people, but all those who have sheltered under the American nuclear umbrella,” he further continued, hinting of the cozy relations between the conservative government in Britain and the Trump administration.

Comparing the situation to the Cold War, the foreign secretary said, “The public can be forgiven for genuinely starting to wonder whether the nuclear sword of Damocles is once again held over the head of a trembling human race.”

Trump has taken a tough stance against Pyongyang, threatening to “totally destroy” North Korea if necessary and calling North Korean leader Kim Jong-un a “rocket man” on a “suicide mission.” North Korea has responded with threats, vowing to take the “highest-level” measures against the US.

Meanwhile, the South Korean military has threatened that it would be quick to totally destroy North Korea’s front-line artillery systems in the event of a war on the peninsula.

The US and the North have been at loggerheads over Pyongyang’s weapons and nuclear programs. However, tensions on the Korean Peninsula have recently risen sharply following a series of weapons tests by Pyongyang, including its sixth and most powerful nuclear test on September 3 and two missiles launched over Japan. Back in July, the North also claimed that it had fired two intercontinental ballistic missiles.

North Korea is under mounting international pressure over its missile and military nuclear programs and has been subjected to an array of sanctions by the United Nations. However, Pyongyang says it needs to continue and develop the programs as a deterrent against the US and its regional allies, including South Korea and Japan.